Inner-city Sydney in the '90s. Yoga for me was synonymous with being a (failed) vegan, flirting with yoga teachers and drinking too many cups of soy chai. I dabbled in Iyengar classes; I gave Hatha a whirl. But it was just a mode of stretching for me, a chance to move my body and be part of a 'cool' community. It wasn't until I began a personal yoga practice 10 years later, in the privacy of my own home, that I began to have an inkling of what it means to do and be yoga.

Since then, I've stopped yoga for months, sometimes more. Two years ago, when I was grappling with a chronic illness, I was given a tailor-made practice by a teacher I trust, and now I've finally found my groove. Every morning, whatever is going on, wherever I need to be, whether I'm travelling or not, I get up and commit to my half hour. It's been astounding. I've started to understand that daily yoga is my way of deeply knowing who I am beyond labels and judgments, of cultivating compassion for myself and the entire world. It goes beyond the other exercise I do: beach sprints and weights and ocean swims. It offers self-insight in a way nothing else does.

I've also come to understand that yoga as we conceive of it in the Western world is mistaken.

We think of yoga primarily as asana, the pose. We're under the impression that it's just another form of exercise. We believe that yoga can be easily taught in a 45-minute session at the local gym. We accept that one-size-fits-all classes, whether they be a sweaty workout or a chilled nidra (yogic sleep), are adequate. We think yoga only works on one obvious level.

Yet asana is only one limb of the eightfold path. In The 'Yoga Sutras' of Patanjali (circa 400 A.D), this path is called ashtanga, literally the eight-limbed. It's a wise prescription for a better life, as incisive and relevant today as when it was written.

The other limbs are yama (ethics and behaviour), niyama (self-discipline and spiritual commitment), pranayama (breath control), pratyahara (focus and concentration), dhyana (meditation) and samadhi (the ultimate ecstasy, or transcending the self). Asana is the third limb; its purpose is to still the mind and ready the body for meditation. Yet on social media, a good-looking asana is touted as the ultimate goal. There is an emphasis on particular poses; the Holy Grail being a sufficiently challenging yet flattering contortion of the body.

And we use yoga to sell product, the same way we use sex.

Adhering to the rules of mainstream advertising, yoga, like sex, has become something only thin, eroticised bodies can enjoy. The images we see in magazines or Instagram feeds are mostly those of middle-class, affluent, white men and women. Yoga has become a $16 billion a year industry in the United States alone, and you can choose from a smorgasbord of styles, as long as they conform to a rigid, standardised Western ideal.

Recently there has been an incremental shift. The African-American plus-size yogini, Jessamyn Stanley, takes photos of her yoga practice and posts them on social media, challenging our notions of beauty, fitness, self-love and acceptability. Sarah Harry is the first teacher in Australia to offer yoga for bigger bodies.

Sandy Stanley, a Californian writer and yoga teacher, looks to the future with both hope and trepidation. She says: "It is only when it isn't trendy anymore that we will begin to see what yoga will become in the West. It's a dilemma: I just hope I will still be able to make a living."

But for now, there's still a lucrative market for yoga and 'spirituality'. We're searching for something, whether that be a devotional tradition, a sense of belonging, or a chance at momentary equanimity. But it's only a soft-core, sexualised spirituality many of us have found, of Lululemon yoga pants, midriff-baring tops and Instagram likes.

Don't get me wrong. I don't have an issue with toned, beautiful bodies, nude or otherwise. But I do have an issue when a supposedly spiritual practice ends up looking like a spread out of Cosmopolitan magazine.

Yoga has become mainstream, and when any fringe movement enters popular culture, its message and power are in danger of being diluted. Body image and fitness have become the primary purpose of yoga in the West.

Why else do yoga teachers routinely advertise their classes with photos of themselves, backlit and lushly styled? Why else do their websites sell everything from coffee mugs to yoga blocks to pants? In India, there are no special 'yoga clothes'. Indians wear anything soft and loose to do yoga. So where exactly did our obsession with Spandex come from?

What is the fundamental essence of yoga? Peace. Freedom from the roots of suffering. Connection with the all and the infinite. Absolute simplicity.

All you need for yoga is yourself. It doesn't have to be in a 'sacred' space. You create the sanctity. You can practice in a quiet, incense-filled room, or conversely, in a crowded park. You can do yoga on a beach or in a hotel room. At the airport while you're waiting for a flight. In the car seat, waiting at a red light.

You don't have to make a big production of it. You don't need expensive clothes. You don't music or recorded mantras or a sweat-inducing, heated studio. You don't need to sweat at all (but you may, if you want to). You don't even need a mat.